I searched the Irish Family History Foundation's database. It contains 12,000,000 surviving rcds for abt 65% of Irish counties. Rcds are increasingly sparse B4 1840, rare B4 1800.
Note 1 - Without a KNOWN parish, the chance of an ancestor's rcds NOT being in this database is AT LEAST 35%.
Note 2 - Only 1/2 of Co. Cork's rcds are in this database.
Note 3 - The RC church kept control over most parish rcds from Tipperary (north). These are ONLY available thru the Tipperary Family History Research center at a substantial fee (regardless of outcome).
For Bernard McManus B 1861 +/- 1 yr in Co. Cavan with the father's forename Michael, I found 1 B rcd for 1860 in Templeport RC parish.
For Marg(aret) McCaffrey B 1868 +/- 1 yr in Co. Cavan with the father's forename John, I found 1 B rcd in 1867 also in Templeport.
A view of the detailed B rcd for each SHOULD show the parent's names.
Possible siblings for Bernard are Bridget 1863, Mary 1868, Peter 1871, and Anne 1858.
Will leave it to you to search the database for Margaret's siblings.
Google the Foundation's name to lead you to this database. Register, opt to be notified as rcds are added and browse. Pls post your search results to my genforum msg.